1. Field of the Invention
The invention relates to accessories for model vehicles, and, more specifically, to a smoke generating device for a model train or other model vehicle.
2. Description of Related Art
Model train engines having smoke generating devices are well known. Some smoke generating devices generate smoke at a substantially constant rate. More sophisticated smoke units may produce smoke at a rate proportional to the speed of the train, or to the loading of the engine of the train. Notwithstanding the advantages of such units, they may be subject to certain disadvantages. Some such units employ a resistive heating element to heat an oil or other smoke generating material. When the smoke unit is operated for a long period of time, or at high output levels, the heat generated by a resistive element may cause the smoke generator to fail, or may pose a safety hazard if not properly controlled.
In addition, some smoke generating devices depend on maintenance of a constant voltage across the heating element of the smoke generating unit to maintain a desired smoke output rate. Power is usually supplied from the model train track, but track voltages may be subject to considerable fluctuations. Therefore, maintaining adequate control over power supplied to the heating element of the smoke generating device may not be possible, or may require expensive electronic controls. Temperature fluctuation may occur in response to fluctuations in voltage supplied to the heating element of the smoke generating unit. When the temperature fluctuates, the smoke output rate may vary. Therefore, smoke output from the smoke generating unit may differ from what is intended or desired.
It is desirable, therefore, to provide an improved smoke generating unit for a model train, that more effectively controls smoke output and reduces the risk of overheating, without adding undue cost or complexity.